A number of very desirable ammoxidation catalysts are known which represent the base catalysts of the invention. These catalysts are used to produce acrylonitrile or methacrylonitrile under certain conditions with high per pass conversions. Under these conditions, if the amount of olefin fed over the catalyst in a given time is increased significantly, the per pass conversion tends to drop. In some instances, the per pass conversion to unsaturated nitriles drops markedly. Since the viability of a commercial operation is significantly affected by the amount of product that can be prepared in a given time, the present invention is directed at the problem in the art of increasing the production of product in a given time while maintaining high per pass conversions.